Obviously mics like this have a specificic audience. I paid about $300 for my powered binaural mics. A $20 eBay mic will work fine for recording lectures where fidelity isn't a requirement but doesn't compare at all with a professional grade mic for recording music.

Thanks for the link OP - this setup looks interesting. The fact that the battery box is made to look like a pager is really an awesome idea for stealth recording. As it stands I have to stash my battery box on my crotch o_O